Traditionally, electronics components are air cooled, often in an enclosure with one or more intake or exhaust fans. Careful design in a fault-tolerant environment suggests there should be more than one fan, in case one fan fails. Modular electronics components introduce additional factors, in that the cooling of the system should be effective whether there is one or many components installed. Some of the components may generate more heat than others. A standard airflow with one pathway and one cooling fan may not suffice for all conditions of operation. Sometimes a component or member obstructs an air passage, reducing air cooling efficiency, especially in a compact and dense configuration. It is within this context that the embodiments arise.